The growth potential expressed as the term optimal weight can also be displayed proportionately for all gestational ages, as the Gestation Related Optimal Weight (GROW).
Together with its upper and lower limits, the customised chart (GROW) 6outlines the growth curves or trajectories along which the fetus is expected to reach its own customised term optimal weight (TOW).
The GROW chart is based on the following three principles:
1. It
is adjusted
for physiological characteristics known to affect fetal
growth: maternal height, weight in early pregnancy, ethnic origin, and parity
(birth order).
(sex is also a factor but is not usually adjusted for prospectively)
2. It excludes pathological factors that may have an effect on fetal growth, such as smoking, diabetes etc.
3. It is based on a fetal rather than a neonatal growth function derived from averaged ultrasound measurements in term pregnancies with normal outcomes. Birth weights from pregnancies delivered preterm (which by definition did not have a normal outcome), are not used in deriving this ‘optimal’ standard.
6. Gardosi J, Mongelli M, Wilcox M, Chang A. An adjustable fetal weight standard.
Ultrasound Obstet Gynecol. 1995 Sep 1;6(3):168–74. https://doi.org/10.1046/j.1469-0705.1995.06030168.x